Intervalometer



Sept 2 1 R. K. BOLE ET AL INTERVALOMETER Filed Feb. 16, 1953 INVENTORS ROBERT K. 001.5 MAURICE H. BALLER By (Q ATTOR NE YS 2,853,563 I INTERVALOMETER Robert K. Bole, Bethesda, Md., and Maurice H. Ballet,

Washington, D. C., assignors to the United States of America as represented by the Secretary of the Navy The invention described herein may be manufactured and used by or for the Government of the .United States of America for governmental purposes without the payment of any royalties thereonorl'therefor.

This invention relates to a selective firing device to control the sequential firing of a battery of rockets or explosives from a suitable launcher and more particularly to an interval switching arrangement whereby a plurality ofelectrical circuits may be opened and closed at prede-' termined time intervals.

Conventional intervalometers utilizing a rotating drum with numerous contacts or selector points necessitate an excessively long drum to accommodate a single terminal bar on which are mounted the contact points-or brushes. In the event that additional contact points were to be added to provide additional contacts many of the existing contact points had to be redistributed on the contactor supporting bar and the drum surface contact positions redesigned in order to cooperatively engage with the newly positioned contact points. Practical limitations of space, size and capacity of the individual drum and contactor supporting bar restricted additional contact areas. Normally additional duplicate units had to be installed to carry the additional changes thereby necessitating not only a duplication of equipment but also a requirement for synchronizing the newly installed unit with the original installation. v r

It is important in a timing device to be used in launching a battery of rockets or explosives that there be provision for a flexible variable fire pattern, adapted to fulfill the requisites for the target to be fired upon. In prior art devices after the initial timing sequence was obtained the cycle of operation was permanently fixed because there was no provision incorporated either on the drum or terminal bars to vary the timing or interval sequence.

The present invention has for an object the use of a compact timing drum affording ample space about its periphery to mount a plurality of parallel spaced terminal bars or strips supporting numerous electrical contactors.

It has for a further object the provision of an intervalometer with a variable time sequence.

A further object is to provide the conductive drum assembly with a greater number of contactor points than were utilized formerly in a timing device.

It also has for its object an apparatus particularly suitable for modifying individual sequential timing intervals requisite in rocket firing to achieve anoptimum target pattern.

, Another object is to simplify the construction of an electrical ignition system which will alford rapid modifica-v tion both to minor variations in timing intervals by shifting the relative distance between terminal bars as well as alteration of the complete firing pattern merely by interh n n v s quen e Pa tern..s. eev -.I

-"A'further' object is to utilize more fullyj 'theffull peg riphery of the drum by providing rows'bt series spaced apertures on ghqdrurn,surface independent of one anthe g sees In carrying the invention into effect, as illustrated by the particular embodiment herein disclosed, a constant speed motor or any constantly rotating energy source may be'used for the prime mover to rotate the intervalometer drum which has an electrically conductive surface. Encompassing the periphery of the drum surface is' a perforated insulating covering material in which. perforations or apertures have been selectively determined to obtain a desired rocket firing pattern. Circumferentially spaced from the cylindrical surface of the drum, mounted on segmental sectors, is a plurality of adjustable terminal strips. Mounted on the individual terminal strips is a series of contactors or brushes, each contactor engaging the perforated covering material on the drum surface in accordance with a predetermined pattern, and upon contact with the conductive surface of the drum an electrical charge is transmitted through the contactor to a connecting lead wire which is in turn connected to a terminal on the rocket launcher, ultimately discharging one rocket from a battery. Relative displacement of the terminal strips alters the sequence of firing and the re sultant fire pattern. Major modifications may be made by substituting another insulating belt or sleevewhich incorporates a modified perforated structure to produce a changed firing sequence.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is an end sectional view taken from a plane, passed normal to the drum axis showing the relative arrangement of the rotatable drum and the circumferentially spaced terminal strips mounted in the arcuate openings of the segmental sectors; and

Fig. 2 is a development of a selected pattern on the insulating sleeve shown in cooperation with the contactors mounted on the terminal strips longitudinally traversing the sleeve and drum. I

Now by reference to the accompanying figures of the drawing, a preferred form which the invention takes will b:- described in detail.

Referring to Fig. l the drum supporting frame 10 rotatably supports the drum shaft 11 which may be driven by a constantly rotating motor or a prime mover directly coupled or connected by a gear or pulley arrangement (not shown). A cylindrical drum 12 mounted on the drum shaft 11 rotates with the shaft 11 in the frame 10. The cylindrical surface 13 of drum 12 is made from an electrically conductive material, preferably copper. This surface may be made integral with the drum or constitute a coated conductive sleeve fastened to the periphery of the drum by any suitable means, such as, by cooperation with drum protuberances 14 (Fig. 2). q

Segmental sectors 15 are securely mounted on the frame 10 parallel to the ends of the cylindrical drum 12, each sector has a continuous arcuate guideway or slot 16 circumferentially spaced from the periphery of the drum 12.

The arcuate guideway 16 within the sector 15 provides a circumferentially spaced slot in which a plurality of terminal strips 17, 18, 19, and 20 are slidably mounted for peripheral displacement about the rotatable drum 12, and the terminal strips are spaced radially equidistant from the surface of the drum 12. Suitable friction fastening means engage each of the terminal strips 17, 18, 19, and 20 through the arcuate guideway 16 retaining the strips in selected position but permitting relative movement about the drum 12 with respect to-the adjacent terminal strips. h

- Terminal strips 17, 1s, 19,15,110 are enumeratin a spaced about'the periphery of the drum 12 parallel to one 1 Patented Sept. 23, 19 58 another and to the longitudinal axis of the drum 12 and maintain this parallel relationship when displaced in any selected position. Each terminal strip of the group 17, 18, 19, and 20 is an elongated narrow nonconductor member extendingover the full Cylindrical width of the drum 12.. Tapped terminal holes 22 spaced equally on each of the terminal strips are to be engaged by wire lead screws or terminal strip posts 23 for retaining individual wire leads 24 thereby connecting the individual contactors 25 of the intervalometer to a selected circuit. Similar connections aremade on each of the terminal strips. Electrically, cooperating with the wire leads 24 affixed to and.

projecting downwardly from the terminal strips 17, 18, 19, and 20 and in surface engagement with the periphery of the drum 12 are series of drum surface contactors 28. .27, 26, 25, respectively, equally spaced along the terminal ""strips. As shown in Fig. 2 a number of single wire leads 24 may be connected to separate drum contactors 25 on terminal strip' 20 through terminal posts 23, however, of rcourse wire leads from other rocket launcher batteries I may be spliced and connected to the single terminal strip .post 23 if desired.

The common ground drum surface contactor 29 and -the wire lead 30 are mounted laterally on terminal strip 20 beyond the series of contactors 25. This ground contactor 29 will engage the electrically conductive surface 13 of the drum 12 during drum rotation to complete the electrical circuit through the drum for each of the contactors in the series 25, 26, 27, and 28.

Encircling the electrically conductive peripheral surface 13 of the drum 12 is an insulating sheet or sleeve 21. Sleeve 21 and drum 12, shown in a developed plan view in Fig 2, is a typical constant interval firing pattern. Series of small rectangular apertures 31, 32, 33, and 34 selectively positioned longitudinally and laterally on the insulating sheet 21 conform to a predetermined firing patternj The desired pattern shown on insulating sleeve 21 has been selected so that the perforated apertures of series 34 are coincidently aligned to cooperate with terminal strip 20 through drum contactors 25; series 33 cooperates with terminal strip 19 through drum contactors 26; series 32 cooperates with terminal strip 18 through drum contactors 27; and series 31 cooperates with terminal strip 17 through drum contacts 28, respectively, in that order as the drum 12 rotates in a clockwise direction as shown in Fig, 1. An elongated ground slot 36 is positioned on insulating sleeve 21 enabling the ground surface contactor 29 to make electrical contact with drum cylindrical surface 13 as the contactors engage the conductive surface of the drum 12.

Theinsulating sleeve 21 is maintained in the correct relative positionon the drum surface 12 by drum protuberances 14 which project through the sleeve 21 to retain perforations 35 cut at suitable locations on the sleeve 21, or. the sleeve 21 may be fastened in place by other suitable fastening means of an adhesive nature.

The electrical circuit is completed to a designated point beyond the intervalometer whenever the drum 12 rotates the conductive cylindrical surface 13 and insulating sleeve 21 so that one drum surface contactor. of the series 25 passes fromabove the insulating sleeve 21 into intimate contact with the electrically conductive drum surface 13 through one of the apertures in the series 34 permitting current to pass through the lead wire 24 and the common ground surface contactor 29 contacting drum surface 13 through the elongated ground slot 36, completing the electrical circuit. The remaining contactors of the series 25 will progressively engage successive apertures in series 34 until exhausted. Then the succeeding terminal strip 19 will have its contactors 26 engage a mating series 33 on the drum periphery in the proper sequence and so on for each of the remaining terminal strips. Altering the relative positions of the terminal strips 17, 18, 19, and 20 will vary the timing sequence between strips and with respect to the other strips. A modified constant firing pattern sleeve may be substituted for that shown in Fig. 2 which will yield a completely changed firing sequence. The combinations which may be produced are sufiiciently flexible and varied to achieve the most desirable fire pattern for any target objective.

Varying the aperture openings longitudinally affords a convenient means for altering the length of time during which the contactor remains in electrical contact with the conductivedrum surface thereby closing the circuit for the desired time interval;

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An intervalometer for use with a multiple explosive launcher to provide a selective firing sequence for firing a battery of rockets, said intervalometer comprising; a rotatably mounted drum, an electrically conductive material securely fastened to and encircling the periphery of the drum, an insulating material with apertures therein substantially covering the conductive material on the drum, projections on the periphery of the drum, said apertures selectively positioned laterally and longitudinally on the insulating material to expose the conductive material through the apertures and to engage the projections on the drum to retain securely the insulating material, segmental sector plates with arcuate openings therein spaced from the opposite ends of said drum, a plurality of terminal strips extending across the drum and circumferentially mounted parallel. to one another and to the drum axis engaging the arcuate for slidable adjustment therein, series of electrically conductive drum surface contactors selectively spaced on the terminal strips and separately mounted to engage electrically the conductive material on the drum through said apertures, and a common ground drum surface contactor on one of said terminal strips to engage electrically the conductive material through series of contactors laterally and circumferentially spaced from each other, thereby completing an electrical circuit which fires individual rockets in accordance with a predetermined firing plan pattern.

2. An intervalometer for use with a multiple explosive launcher to provide a flexible variable fire pattern for sequence firing of a battery of rockets, comprising a row conductive surface with circumferentially spaced series of circumferentially and laterally spaced apertures. and with an elongated slot, said apertures and slot exposing the conductive surface of said drum, segmental sector plates spaced from opposite ends of said drum, each sector plate having an arcuate guideway spaced from the periphery of said drum, a plurality of elongated terminal strips slidably mounted in said guideway of said sector plates extending across the drum and spaced therefrom parallel to one another and to the drum axis, series of electrically conductive drum surface contactors selectively laterally spaced on each of the terminal strips and separately mounted, said contactors engaging electrically the conductive surface on the drum through said apertures of said sleeve, and a common ground drum surface contactor on one of said terminal strips engaging electrically the conductive surface through said elongated slotof said insulating sleeve thereby completing an electrical circuit which fires'the rockets of the battery in accordancewith a predetermined firing plan established by the arrangement of the apertures and the placement of the terminal-strips in the guideways.

(References on following page) openings in the sector plates.

one of said apertures, each:

5 References Cited in the file of this patent UNITED STATES PATENTS Johnson Mar. 24, 1891 Giles et a1 July 12, 1921 5 Bowker Dec. 13, 1921 Edwards Sept. 4, 1923 Carlson et a1. June 20, 1939 6 Zimarik Nov. 4, 1942 Lambert et a1 June 10, 1947 Metzger May 4, 1948 Oakley Nov. 30, 1948 Haberman Aug. 2, 1949 Nims et a1. Nov. 15, 1949 

